Synopsis Fertility and plant size were the most important components of seed yield. Inasmuch as fertility and plant size were negatively correlated, r = −.665, a compromise must be reached in selection for these two characters if maximum seed yields are to be obtained. The method of “path coefficients” proved useful in analyzing correlation coefficients in this system of interrelated variables.

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Karyotypes were analyzed on 24 diploid taxa (mostly perennials) belonging to eight Triticeae genera, which are defined by genome content (basic set of seven chromosomes): (i) Agropyron (P genome), (ii) Thinopyrum (J genome), (iii) Secale (R genome), (iv) Hordeum (i genome), (v) Pseudoroegneria (S genome), (vi) Psathyrostachys (N genome), (vii) Australopyrum (W genome), and (viii) Critesion (H genome). In addition to traditional karyotype preparations, the metaphase root-tip chromosomes were analyzed by an interactive microcomputer program that printed an idiogram in which chromosomes were arranged by length. Genomes, arranged by decreasing length, are R, I, P, N, J, S, H, and W (with lengths ranging from 61.29 to 39.39 μm). Almost without exception, karyotypes of species within a genus manifest a pattern that is unique to the genome. Morphologically unique genomes are useful diagnostic features in genome identification and can complement interpretation of chromosome pairing in genome analysis.Key words: Triticeae, diploid, karyotype, genome relationship.

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This paper reports for the first time on the mode of pollination of many perennial Triticeae grasses and evaluates the mode of pollination as it relates to the genomically dr:fined genera of Dewey (1984). Self fenility was estimated by counting seed set on spikes that were enclosed in an isolation paper bag prior to anthesis to exclude foreign pollen. The latter genera can be grouped as follows: (1) Self-fertility was determined by measuring seed set on spikes that had been enclosed in white paper bags (7.5 cm x 66 cm) prior to anthesis to exclude For personal use only. The most self-fertile taxon of Pseudoroe-gneria was tetraploid (2n:28) P. spicata.The three most self-fertile plants averaged 22.0, 3\ 0, and 37 .6 self seeds per spike, whereas '7 of the 56 plants produced no self seeds on five spikes. Tetraploid P. stipfolia (Czern. ex. Nevski) A' . Lcive was also considerably more self-fertile than diploid P. sripifulia (Table 3). In spite of the presence of individual plants with quite high self-fertility, the genur; Pseudoroegneria must be considered as normally cross-pollinating.